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VERIFICATION OF CORRECT BATTERY FOR INTRINSICALLY SAFE RADIOS

IP.com Disclosure Number: IPCOM000008179D
Original Publication Date: 1997-Jun-01
Included in the Prior Art Database: 2002-May-23
Document File: 3 page(s) / 112K

Publishing Venue

Motorola

Related People

Christopher W. Wright: AUTHOR

Abstract

The architecture for the JEDI Cenelec, intrinsically safe radio is based around a special battery which provides a dual voltage source, a high voltage, high current supply for the RF power amplifier and a lower voltage, lower current supply for the remainder of the circuitry (Figure 1). It is useful, important and indeed, safety-critical, to be able to indicate to the user that the correct battery has been fitted before the radio is placed into service.

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MO-LA Technical Developments

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VERIFICATION OF CORRECT BATTERY FOR INTRINSICALLY SAFE RADIOS

by Christopher W. Wright

  The architecture for the JEDI Cenelec, intrinsically safe radio is based around a special battery which provides a dual voltage source, a high voltage, high current supply for the RF power amplifier and a lower voltage, lower current supply for the remainder of the circuitry (Figure 1). It is useful, important and indeed, safety-critical, to be able to indicate to the user that the correct battery has been fitted before the radio is placed into service.

  Although a Cenelec battery has a somewhat different appearance, a red label on the inner face, warning text etched onto the outer face and a blue dot on the lower edge, an untrained operator might, inadvertently, fit a standard battery to the radio (Figure 2). As a result, the radio is no longer intrin- sically safe but, in addition, the operator may believe that the radio is operational because it powers up in the normal way, completing a self- check routine and turning on the display. The receiver will function but there will be no supply voltage for the RF power amplifier, no RF output power and, hence, communication over any distance will be impossible.

  A conventional solution to this problem is to design the intrinsically safe radio and battery with some form of mechanical interlock system to prevent the attachment of a non-approved accessory such as a standard battery. A drawback of this approach is the high tooling cost for a relatively low

volume product whereas the proposed, electronic methods, allow use of the standard mechanics for radio and battery.

  A simple low-cost solution would be to add a connection between the PA B+ line from the battery to the ra...